FlightGear comes with a set of illustrated documentation, notably "The Manual," which is included in the installation package. This wiki provides additional documentation on both user and development topics.

Dated March 18, 1999, 20 years ago this week, this little gem is one of the oldest surviving screenshots of FlightGear. Relatively pale compared to current versions of FlightGear, this image shows a very basic landscape, a newly textured sun (with halo), and a very small crescent moon. Back then, FlightGear was the only PC based flight simulator rendering the Sun, Moon, and celestial objects at the correct position, and under the correct lighting conditions, in the sky. (author Durk)